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In this article, the thermoelectric properties of five different polymorphs of gallium phosphide (GaP) such zinc-blende (zb-GaP), wurtzite (wz-GaP), sphalerite (sp-GaP), Beryllium oxide (β-BeO-GaP), and Silicon carbide (SiC-GaP) have been reported in detail. In this regard, the prerequisite electronic structure calculations have been performed in the framework of density functional theory (DFT), whereas the results for thermoelectric properties have been obtained via Boltzmann transport theory (BTT). We found that these GaP polymorphs exhibit relatively higher electrical conductivity corresponding to holes as a result larger power factors (PFs) have been realized for n-type doping than p-type. The highest values of PF corresponding to n-type doping have been recorded as 27.492 × 1010 W/mK2s, 27.999 × 1010 W/mK2s, 29.491 × 1010 W/mK2s, 15.706 × 1010 W/mK2s, and 26.557 × 1010 W/mK2s respectively, for zb-GaP, wz-GaP, sp-GaP, β-BeO- GaP, and SiC-GaP. Moreover, their PF has been further enhanced by the increase in temperature. In contrast, the Seebeck coefficients (thermopowers) have been found relatively larger for p-type doping than n-type. The relatively large thermopowers and lower thermal conductivity for p-type doping have resulted in the enhancement of Figure-of-merit (zT) by holes rather than electrons. The highest zT values have been recorded as 0.997, 1.004, 0.998, 1.001, and 1.010 in the case of zb-GaP, wz-GaP, sp-GaP, β-BeO-GaP, and SiC-GaP respectively. Our study indicates the adequate potential of these different polymorphs of GaP for thermoelectric applications.

Epitaxial layers of the solid solution of molecular substitution (Si2)1-x(GaP)x (0 ≤ x ≤ 1) on Si (111) and GaP (111) substrates are grown by liquid-phase epitaxy from an Sn solution-melt. Such graded-gap solid solutions allow the integration of well-established silicon technology with the advantages of III-V semiconductor compounds. The structural features, the distribution of the atoms of the components over the thickness of the epitaxial layer, the photoluminescence spectrum of the (Si2)1-x(GaP)x (0 ≤ x ≤ 1) solid solution, and the electroluminescence of the structure n-GaP-n+-(Si2)x (GaP)1-x (0 ≤ x ≤ 0.01) have been investigated. It is shown that the layers of the solid solution have a perfect single-crystal structure with the crystallographic orientation (111), with the size of subcrystallites ∼ 39 ± 1 nm. The epitaxial layer (Si2)1-x(GaP)x (0 ≤ x ≤ 1) is a graded-gap layer with a smoothly and monotonically varying composition from silicon to 100% GaP. The energy levels of atoms of Si2 molecules which are located 1.47 eV below the bottom of the conduction band of gallium phosphide are revealed. Red emission of n-GaP-n+-(Si2)x(GaP)1-x (0 ≤ x ≤ 0.01) structure which is caused by electron transitions with participation of energy levels of Si2 atoms is detected.

The polytypism of solids has been established as one of the most effective approaches to alter their physical properties. In this first-principles-based study, we practiced the polytypism of galliu...

Photoelectrosynthetic materials provide a bioinspired approach for using the power of the sun to produce fuels and other value-added chemical products. However, there remains an incomplete understanding of the operating principles governing their performance and thereby effective methods for their assembly. Herein we report the application of metalloporphyrins, several of which are known to catalyze the hydrogen evolution reaction, in forming surface coatings to assemble hybrid photoelectrosynthetic materials featuring an underlying gallium phosphide (GaP) semiconductor as a light capture and conversion component. The metalloporphyrin reagents used in this work contain a 4-vinylphenyl surface-attachment group at the β-position of the porphyrin ring and a first-row transition metal ion (Fe, Co, Ni, Cu, or Zn) coordinated at the core of the macrocycle. In addition to describing the synthesis, optical, and electrochemical properties of the homogeneous porphyrin complexes, we also report on the photoelectrochemistry of the heterogeneous metalloporphyrin-modified GaP semiconductor electrodes. These hybrid, heterogeneous-homogeneous electrodes are prepared via UV-induced grafting of the homogeneous metalloporphyrin reagents onto the heterogeneous gallium phosphide surfaces. Three-electrode voltammetry measurements performed under controlled lighting conditions enable determination of the open-circuit photovoltages, fill factors, and overall current–voltage responses associated with these composite materials, setting the stage for better understanding charge-transfer and carrier-recombination kinetics at semiconductor|catalyst|liquid interfaces.

Schottky barriers (SBs) based on gallium phosphide (GaP) attract researchers’ attention as promising structures for the development of various types of radiation-resistant electronic and photovoltaic devices, including high-temperature devices, high-frequency power electronics, ultraviolet (UV) photoelectronics and solar energy. This work studies photoelectric properties of surface-barrier (SB) structures of Au-palladium-n-GaP in the visible spectrum range under the action of both natural and polarized radiation, in order to obtain new data on the barrier height, band structure of GaP and the interface metal semiconductor.In particular, nanostructured Au-palladium-n-GaP structures were examined.The initial material for the structures production - n-GaP plates [n = (0.1-5) · 1017 cm-3, 300 K] with a thickness of 350-400 µm, oriented in the crystallographic plane (100), grown with the Czochralski method. Studying photosensitivity of nanostructured structures of the Au-Pd-n-GaP type in the visible spectrum range gives important information about the parameters of the potential barrier, the band structure of the semiconductor. Thus, the intermediate Pd (palladium) nanolayer between GaP and Au with a thickness of 20-30 A creates specific properties in the Au-Pd-n-GaP nanostructure that are of great scientific and practical importance.

In this paper, the optical and luminescent properties of gallium phosphide (GaP) and spectral characteristics of GaP p-n, m-s structures for studying the energy-band structure of GaP were considered. Based on literature data, the absorption coefficient dependence was constructed near and above the fundamental absorption edge of the photon energy hν=2-6 eV in GaP (300 K) to discuss the obtained experimental results. The results of the photosensitivity spectra study of Au-n-GaP, Au-p-GaP Schottky barriers are presented, which were produced by the chemical deposition of Au nanoscale (~15 nm) on the GaP surface. By comparing the absorption spectrum of GaP with the photocurrent spectra of Au-n-GaP and Au-p-GaP structures in the visible and ultraviolet (UV) region of the spectrum, it has been established that usually the photocurrent (

The article presents the results of a simulation of changes in gallium phosphide (GaP) resistivity under the influence of lighting. The adopted model of the defect structure is presented along with the defect parameters. Initial conditions created on the basis of a tested material sample, labeled GaP-1, made of monocrystals of semi-insulating gallium phosphide (SI GaP), are presented. The simulation methodology and the created model of the kinetics equations are described. As a result of the simulation, the values of the photocurrent and the electron-hole pair generation coefficient G were assigned to data obtained experimentally depending on the carrier lifetime coefficient τ. Changes in resistivity and concentration of electrons and holes in the bands for gallium phosphide with a structure consisting of five defects are presented. The proposed simulation method can be used to calculate switch-on and -off times and photocurrent values for the semiconductor materials used to construct PCSS (photoconductive semiconductor switches) and other electronic devices.

Self-healing materials have recently received considerable attention for improving the Li storage in anodes with high theoretical capacity that suffer from the mechanical instability triggered by the large volume change that occurs during electrochemical reactions. Ga has recently been explored for self-healing liquid metal electrodes in Li-ion batteries because it can be melted near room temperature. Previous reports have demonstrated the ultra-long cycling stability of these Ga-based electrodes owing to their self-healing properties. Unfortunately, despite these efforts, the performance of these Ga-based self-healing electrodes have not been fully satisfactory, particularly in terms of capacity. More importantly, the self-healing mechanism of liquid Ga has not been clearly investigated. Here, we synthesized GaP as a novel self-healing anode with an ultra-high capacity and stability. Self-healing in this Ga-based alloy occurred via the liquid-solid-liquid transition of Ga during lithiation/delithiation. In addition, by confining the liquid Ga in an appropriate binder (poly(acrylic acid)) through strong hydrogen bonding, stable cyclic behavior of the GaP was achieved. Furthermore, the TiO2-C hybrid matrix promoted the mechanical integrity and electrical conductivity of the GaP (GaP@TiO2-C). Consequently, the GaP@TiO2-C electrode showed superb cyclic performance (1012.0 mAh g−1 at 0.5 A g−1 after 500 cycles) and great rate capability. Various post-mortem analyses, including X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy, revealed the in-depth electrochemical reaction and self-healing mechanism of the GaP electrode. This study provides insight into the development of self-healing electrodes with high capacities and long cycling stabilities.

Despite the large number of III–V semiconductor studies reported every year at bulk level, the III–V material characterization at nanoscale is still required to evaluate their potential industrial applications in nanoscale electronic devices, optoelectronic devices, chemical, biosensors, etc. In this work, the non-destructive evaluation-based ultrasonic theoretical approach for the material characterization of nanostructured IIIrd group phosphides, namely indium phosphide (InP), aluminum phosphide (AlP), gallium phosphide (GaP), and boron phosphide (BP) with wurtzite crystal phase, has been reported. The second- and third-order elastic constants (SOECs and TOECs) for IIIrd group phosphides have estimated using the Lennard–Jones potential. The mechanical properties and the ultrasonic investigation of the IIIrd group phosphides materials, e.g., ultrasonic velocities, Gruneisen parameters, acoustic coupling constants, and ultrasonic attenuation, have been performed using the estimated values of SOECs and TOECs. The present investigation indicates that the ultrasonic attenuation of IIIrd group phosphides is influenced by the wave velocities and the chosen material’s thermal conductivity. The other thermophysical parameters like the crystal energy density, the specific heat per unit volume, thermal conductivity, and the Debye temperature of these materials have also been reported at room temperature (300 K). The results indicate that BP is the most robust material and has superior elastic, mechanical, and thermal characteristics.

Resonant metasurfaces are an attractive platform for enhancing the non-linear optical processes, such as second harmonic generation (SHG), since they can generate very large local electromagnetic fields while relaxing the phase-matching requirements. Here, we take this platform a step closer to the practical applications by demonstrating visible range, continuous wave (CW) SHG. We do so by combining the attractive material properties of gallium phosphide with engineered, high quality-factor photonic modes enabled by bound states in the continuum. For the optimum case, we obtain efficiencies around 5e-5 % W$^{-1}$ when the system is pumped at 1200 nm wavelength with CW intensities of 1 kW/cm$^2$. Moreover, we measure external efficiencies as high as 0.1 % W$^{-1}$ with pump intensities of only 10 MW/cm$^2$ for pulsed irradiation. This efficiency is higher than the values previously reported for dielectric metasurfaces, but achieved here with pump intensities that are two orders of magnitude lower.

This study experimentally tests a combination of thermal conductivity and viscosity characteristics for maximum heat transfer using therminol 55 Nanoplastic gallium phosphide (GaP). Recent studies ...

The integration of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) gives better prediction of the system properties towards the applications like water-splitting and gas storage capacity/mechanism. The pursuit of generating low-cost and effective catalyst for such purposes has motivated the material scientists and researchers to design and study the novel nanostructured materials both theoretically and experimentally. We have utilized the well-established state-of-the-art density functional theory (DFT) for envisaging the HER activity of the two-dimensionally confined Gallium Phosphide (GaP). The effect of substitutional defect caused by foreign atoms like boron and nitrogen on the structural, electronic and adsorption properties of the GaP nanowire is analyzed by incorporating the van der Waals dispersion correction. The energy differences and the contributions of the individual atomic species to the electronic energy states have been observed by computing the electronic density of states. Introduction of the defect in the system significantly modifies the electronic and adsorption properties of the system. The results suggest GaP to be highly active for hydrogen adsorption which further gets pronounced by introducing boron defect in the system. The results on adsorption energy and Gibbs free energy stipulating better adsorptive nature for hydrogen give confidence to utilize GaP as an HER catalyst by further tuning the adsorption response by means of defect engineering. In a nut-shell, we assert the dependence of material properties that are very sensitive to defects and the cause root beneath this response can serve as a blueprint for designing prominent materials for HER based applications.

Gallium phosphide can be considered as a prospective material for impurity band solar cell (IBSC), if sufficient amount of an appropriate impurity (Ti in our case) is introduced to the material by ...

The paper shows the results of the development of a photodiode technology based on gallium phosphide structure n+-n-GaP-Au with high sensitivity. It provides the ion etching of the surface of the gallium phosphide before an application of a leading electrode of gold. The barrier layer of a 20 nm thick gold is applied to the substrate in the magnetic field of GaP. When forming the contact with the reverse side of the indium substrate at 600°C, there occurs the annealing of the gold barrier layer. At the maximum of the spectral characteristics obtained by the photodiode, it has a sensitivity of 0.13 A/W, and at a wavelength of 254 nm – about 0.06 A/W. The dynamic range of the photodiode is not less than 107.

The photovoltaic characteristics of a mechanically and monolithic stacked tandem solar cell of the heterojunction InGaP/GaAs and Ge sub cells, were numerically simulated under 1-sun air mass 1.5 global spectrum (AM1.5G) at ambient temperature (300 K) using the two-dimensional device simulator Silvaco–Atlas. Our tandem structure consists of a thin upper cell with heterojunction of indium and gallium phosphide on gallium arsenide (In0.49Ga0.51P/GaAs), on a relatively thick germanium (Ge) substrate which acts as a lower cell in order to obtain good performances of such a structure. We studied both cells, stacked mechanically (four terminal:4T) and monolithic (two terminal:2T) using Silvaco ATLAS Virtual Wafer FabricationTool. First, we have simulated the single InGaP/GaAs and Ge solar cells with fixed thicknesses at 1.4 µm and 210 µm respectively. They presented a conversion efficiencies (ƞ) of 30.32% and 10.96% respectively. The efficiency of mechanically stacked tandem solar is 30.96% and short current density of 26.16 mA/cm2 which is limited by the lower short current density of both sub-cells. Using the method of current matching, by varying the base thicknesses of the InGaP/GaAs top and Ge bottom sub-cells, the numerical simulation results presented a matched maximum current Jsc value of 29.12 mA/cm2 obtained at base thicknesses of 0.605 and 209.9 μm for the InGaP/GaAs top and Ge bottom sub-cells respectively, leading to a high power conversion efficiency (ƞ) of the mechanically stacked sub cells of 34.77%, the open-circuit voltage and the fill factor are 1.329 V and 88.96%, respectively. Next, the sub-cells were interconnected with tunnel junctions (TJs), p-GaAs/n-GaAs to allow carrier transport, the results of the monolithic stacked sub-cells are converged with results of the mechanically stacked sub-cells, and are represented in the following results of the tandem cell: power conversion efficiency (ƞ) of 32.96%, the open-circuit voltage of 1.343 V, the short current of 29.19 mA/cm2 and the fill factor of 84.05%.

In this article, a first-principles based simulation framework is presented to project the performance of a novel 2-D field-effect transistor (FET) under the ballistic limit. Our framework consists of: 1) density functional theory modeling of the novel 2-D material that gives accurate electronic structure without requiring parameters; 2) mode-space transformation; 3) spectral adjustment to maximize computational efficiency; 4) extraction of the dielectric constant of the novel 2-D material using a first-principles approach; and 5) nonorthogonal nonequilibrium Green’s function method for accurate quantum transport simulations. We have applied our framework to evaluate the device performance of novel silicene/gallium phosphide (Si/GaP) heterobilayer FETs. Our results reveal that Si/GaP FETs have a great potential for high-performance logic devices, with high ON-state current, low subthreshold swing, and high speed with small dynamic power consumption.

In this work, the effects of x-value on electrical and optical properties was studied for the two dimensional (2D)GaAs1-xPxstructure by applying the density functional theory.We found that the gallium arsenide(GaAs) and gallium phosphide(GaP) monolayers are bound to each other, while the charge transfer between these two materialsleads to tuning the band gap value between 1.5 eV for GaAs to 2.24 eV for GaP. The density of state, band structure, and optical properties are investigated in this paper.

International audience; A new process to produce orientation-patterned gallium phosphide (OP-GaP) on GaAs with almost perfectly parallel domain boundaries is presented. Taking advantage of the chemical selectivity between phosphides and arsenides, OP-GaP is processed into suspended shallow-ridge waveguides. Efficient second-harmonic generation from telecom wavelengths is achieved in both Type-I and Type-II polarisation configurations. The highest observed conversion efficiency is 200% W–1 cm–2, with a bandwidth of 2.67 nm in a 1 mm-long waveguide. The variation of the conversion efficiency with wavelength closely follows a squared cardinal sine function, in excellent agreement with theory, confirming the good uniformity of the poling period over the entire length of the waveguide.

Gallium phosphide (GaP) solar cell structures with improved quantum efficiencies were realized using a modified liquid phase epitaxy (LPE) technique and diodes formed using semi-transparent Schottky contacts. The improvement is due to the addition of a small amount of aluminum to the gallium and phosphorus containing LPE melt. The Al reduces the background concentration of oxygen in the melt, which is known to produce deep trap states in GaP. Additionally, it was found that by depositing an aluminum (Al)-rich AlGaP layer on top of the active GaP and then selectively etching it away, the surface morphology of the active layer was significantly improved. Thus, the modified LPE technique eliminates the major problem of meniscus lines associated with the standard LPE method.

Chloride-hydride epitaxy is the main vapor-phase technique for forming layers of functional homostructures and heterostructures for microelectronics and optoelectronics. At present, nanoheterostructures are obtained by MOS-hydride and molecular epitaxy; the molecular-layering technique is currently being perfected. The occurrence of new materials requires long-term development of the optimal technological conditions for their fabrication and the mathematical, physical, and other principles for modeling these processes. The chloride-hydride method continues to be perfected for forming relatively thick layers of functional heterostructures. The work outlines the fundamentals of physicochemical modeling by the example of chloride-hydride epitaxy. A physicochemical model of the variation in the technological modes of the vapor-phase epitaxy of different compounds under the corresponding conditions, which facilitate the formation of compounds with the same degree of disorder, is discussed. Equations for predicting the conditions for the epitaxy of other materials of the same group by the well-developed technology of a material have been derived. The obtained regularities can be used to optimize the chloride-hydride epitaxy of gallium phosphide and solid solutions based on it. The calculated conditions for gallium-nitride epitaxy are shown to be in good agreement with the conditions of real technological developments made by other authors.

Gallium phosphide (GaP) is an indirect bandgap semiconductor used widely in solid-state lighting. Despite numerous intriguing optical properties---including large $��^{(2)}$ and $��^{(3)}$ coefficients, a high refractive index ($>3$), and transparency from visible to long-infrared wavelengths ($0.55-11\,��$m)---its application as an integrated photonics material has been little studied. Here we introduce GaP-on-insulator as a platform for nonlinear photonics, exploiting a direct wafer bonding approach to realize integrated waveguides with 1.2 dB/cm loss in the telecommunications C-band (on par with Si-on-insulator). High quality $(Q> 10^5)$, grating-coupled ring resonators are fabricated and studied. Employing a modulation transfer approach, we obtain a direct experimental estimate of the nonlinear index of GaP at telecommunication wavelengths: $n_2=1.2(5)\times 10^{-17}\,\text{m}^2/\text{W}$. We also observe Kerr frequency comb generation in resonators with engineered dispersion. Parametric threshold powers as low as 3 mW are realized, followed by broadband ($>100$ nm) frequency combs with sub-THz spacing, frequency-doubled combs and, in a separate device, efficient Raman lasing. These results signal the emergence of GaP-on-insulator as a novel platform for integrated nonlinear photonics., 13 pages, 10 figures, 1 table; typos corrected, added/fixed references, modified title

Indium gallium phosphide (InGaP) solar cell with a superior high-radiation resistance is expected to be a powerful candidate for a dosimeter under a high-radiation dose rate environment. In...

Single photon emitters in atomically-thin semiconductors can be deterministically positioned using strain induced by underlying nano-structures. Here, we couple monolayer WSe2 to high-refractive-index gallium phosphide dielectric nano-antennas providing both optical enhancement and monolayer deformation. For single photon emitters formed on such nano-antennas, we find very low (femto-Joule) saturation pulse energies and up to 104 times brighter photoluminescence than in WSe2 placed on low-refractive-index SiO2 pillars. We show that the key to these observations is the increase on average by a factor of 5 of the quantum efficiency of the emitters coupled to the nano-antennas. This further allows us to gain new insights into their photoluminescence dynamics, revealing the roles of the dark exciton reservoir and Auger processes. We also find that the coherence time of such emitters is limited by intrinsic dephasing processes. Our work establishes dielectric nano-antennas as a platform for high-efficiency quantum light generation in monolayer semiconductors., Single photon emitters (SPEs) in 2D semiconductors can be deterministically positioned using localized strain induced by underlying nanostructures. Here, the authors show SPE coupling in WSe2 to GaP dielectric nanoantennas, substantially increasing quantum efficiency and photoluminescence brightness.

Tailoring optical properties in photocatalysts by nanostructuring them can help increase solar light harvesting efficiencies in a wide range of materials. Whereas plasmon resonances are widely employed in metallic catalysts for this purpose, latest advances of nonradiative, dielectric nanophotonics also enable light confinement and enhanced visible light absorption in semiconductors. Here, a design procedure for large-scale nanofabrication of semiconductor photoelectrodes using imprint lithography is developed. Anapole excitations and metasurface lattice resonances are combined to enhance the absorption of the model material, amorphous gallium phosphide (a-GaP), over the visible spectrum. It is shown that cost-effective, high sample throughput is achieved while retaining the precise signature of the engineered photonic states. Photoelectrochemical measurements under hydrogen evolution reaction conditions and sunlight illumination reveal the contributions of the respective resonances and demonstrate an overall photocurrent enhancement of 5.7, compared to a planar film. These results are supported by optical and numerical analysis of single nanodisks and of the upscaled metasurface.https://onlinelibrary.wiley.com/doi/10.1002/aenm.202102877

We demonstrate highly efficient second harmonic generation from dielectric meta-surfaces based on gallium phosphide platform, utilizing quasi-bound-state-in-the-continuum resonances. In particular, we demonstrate an efficiency of 0.1 %/W using pulsed laser at an intensity of 10 MW/cm2 and 5e-5 %/W using continuous wave laser at an intensity of 1 kW/cm2.

The article analyzes the morphological characteristics of a porous GaP surface layer formed on the surface of monocrystalline gallium phosphide by electrochemical etching. The correlations between the etching time and the appropriate size, shape and density of pores have been established and studied in detail.

Optical resonances arising from quasi-bound states in the continuum (QBICs) have been recently identified in nanostructured dielectrics, showing ultrahigh quality factors accompanied by very large electromagnetic field enhancements. In this work, we design a periodic array of gallium phosphide (GaP) elliptical cylinders supporting, concurrently, three spectrally separated QBIC resonances with in-plane magnetic dipole, out-of-plane magnetic dipole, and electric quadrupole characters. We numerically explore this system for second-harmonic generation and degenerate four-wave mixing, demonstrating giant per unit cell conversion efficiencies of up to ∼ 2 W−1 and ∼ 60 W−2, respectively, when considering realistic introduced asymmetries in the metasurface, compatible with current fabrication limitations. We find that this configuration outperforms by up to more than four orders of magnitude the response of low-Q Mie or anapole resonances in individual GaP nanoantennas with engineered nonlinear mode-matching conditions. Benefiting from the straight-oriented electric field of one of the examined high-Q resonances, we further propose a novel nanocavity design for enhanced spectroscopies by slotting the meta-atoms of the periodic array. We discover that the optical cavity sustains high-intensity fields homogeneously distributed inside the slot, delivering its best performance when the elliptical cylinders are cut from end to end forming a gap, which represents a convenient model for experimental investigations. When placing an electric point dipole inside the added aperture, we find that the metasurface offers ultrahigh radiative enhancements, exceeding the previously reported slotted dielectric nanodisk at the anapole excitation by more than two orders of magnitude.

Most researchers proposed the surface plasmon resonance (SPR) sensor in the visible light range only. This paper presents performance enhancement of SPR sensor based on molybdenum disulphide (MoS 2 )-Dielectric matertals-MoS 2 -structure in Near Infrared (NIR) region for urea detection. The proposed structure consists of six layers, and the gold (Au) is used as a plasmonic material to improve its performance. The double MoS 2 layers are coated on both surfaces of dielectric materials such as germanium oxide (GeO 2 ) and gallium phosphide (GaP), which are used as protective layers and bio-recognition elements to enhance SPR performance. In this study, we have considered two different urea concentrations of 2.5 and 5gm/dl as a sensing medium, having RIs of 1.339 and 1.342, whereas the normal urea RI is 1.335. The performance is analyzed numerically at 785nm wavelength applying the transfer matrix method. Initially, the performance investigates the optimized thickness of Au using the iteration method. Further, the outcome results are shown in terms of sensitivity and quality factor (QF), and the maximum achieved performances are S of 280°/RIU and QF of 41.36RIU−1 at a change in sensing RI of 0.007. Finally, the proposed structure performance is compared to existed SPR structures done by other researchers.

We report a semiconductor contact grating terahertz source design based on a rectangular profile for phase-matched terahertz generation in the long infrared pump wavelength range. The calculations show that the best diffraction efficiency can be achieved by a filling factor significantly smaller than 50%. Furthermore, the possibility of diffraction efficiency enhancement was investigated by applying three different antireflective coating structures. Numerical simulations have indicated that at 2.06 μm and 3.0 μm pump wavelength, diffraction efficiencies greater than 91% and 89% can be achieved by adding an appropriate antireflective coating to the GaP and GaAs contact grating structure, respectively. In addition, numerical simulations were performed to investigate the influence of wall angles on diffraction efficiency. The results reveal that the wall angle does not significantly affect the diffraction efficiency: while keeping the wall angle deviation from the vertical below 25 degrees, the efficiency drop remains below 5% for otherwise optimal grating parameters.

Tailorable synthesis of III-V semiconductor heterostructures in nanowires (NWs) enables new approaches with respect to designing photonic and electronic devices at the nanoscale. We present a comprehensive study of highly controllable self-catalyzed growth of gallium phosphide (GaP) NWs on template-free silicon (111) substrates by molecular beam epitaxy. We report the approach to form the silicon oxide layer, which reproducibly provides a high yield of vertical GaP NWs and control over the NW surface density without a pre-patterned growth mask. Above that, we present the strategy for controlling both GaP NW length and diameter independently in single- or two-staged self-catalyzed growth. The proposed approach can be extended to other III-V NWs.

High harmonic generation (HHG) opens a window on the fundamental science of strong-field light-mater interaction and serves as a key building block for attosecond optics and metrology. Resonantly enhanced HHG from hot spots in nanostructures is an attractive route to overcoming the well-known limitations of gases and bulk solids. Here, we demonstrate a nanoscale platform for highly efficient HHG driven by intense mid-infrared laser pulses: an ultra-thin resonant gallium phosphide (GaP) metasurface. The wide bandgap and the lack of inversion symmetry of the GaP crystal enable the generation of even and odd harmonics covering a wide range of photon energies between 1.3 and 3 eV with minimal reabsorption. The resonantly enhanced conversion efficiency facilitates single-shot measurements that avoid material damage and pave the way to study the controllable transition between perturbative and non-perturbative regimes of light-matter interactions at the nanoscale., Strong nonlinearities, like high harmonic generation in optical systems, can lead to interesting applications in photonics. Here the authors fabricate a thin resonant gallium phosphide metasurface capable of avoiding the laser-induced damage and demonstrate efficient even and odd high harmonic generation from it when driven by mid-infrared laser pulses.

Between two-dimensional (2D) semiconductors, the family of transition metal dichalcogenides (TMDs) exhibits promising optical properties, such as tightly bound excitons and single photon emitting centers, with favourable integration in current nano-photonic architectures. High refractive-index dielectrics have recently gained attention as they exhibit optical Mie resonances, offering a novel platform to engineer light-matter interaction down to sub-wavelength dimensions. In our work, we integrated single and double layer TMDs WSe 2 with Mie-resonant gallium phosphide (GaP) dimer nano-antennas and demonstrate the enhancement of the light-matter interaction of 2D excitons and relative single photon emitters.

Semiconductor nanowires (NW) have received much attention for their unique properties providing exceptional flexibility in device engineering. In particular, gallium phosphide NWs demonstrate effective wave-guiding properties and broadband nonlinear frequency conversion, and find applications in green to amber optical range optoelectronics and photocatalytic devices. They also exhibit one of the broadest transparency range, high values of the nonlinear refractive index and good thermal conductivity that make them perspective for nanophotonics.

Gallium Phosphide (GaP) is a material with outstanding optical properties and a promising candidate for nanophotonic applications. Among comparable materials, it is one with the highest linear refractive indices and due to its wide and indirect bandgap, it has a lossless transparency for wavelengths longer than 450 nm. The bulk crystal was already shown to have a strong ultrafast response [1] and nanostructuring of a GaP wafer led to a record conversion efficiency in second-harmonic generation (SHG) [2] . Nevertheless, such structures are based on a high refractive index substrate and therefore no optical contrast in that direction. This prevents strong optical resonances and therefore naturally limits nonlinear efficiencies.

The paper presents a numerical simulation of novel Indium Nitride and Gallium Phosphide based GaN-BTG (Buffer Trenched Gate) MOSFET. The electrical characteristics such as Transfer characteristics, Transconductance, Electron mobility of InN-GaN-BTG-MOSFET and GaP-GaN-BTG-MOSFET are exhaustively analyzed using the Atlas TCAD tool. A comprehensive study is presented comparing the InN-GaN-BTG-MOSFET with GaN-BTG and GaP-GaN-BTG MOSFETs in terms of their performance characteristics. An improvement of 60.48% in SS and an increment of 47.16% in the electric field is observed which is because of the appliance of GaP and InN in the GaN-BTG structure. InN-GaN-BTG-MOSFET proves to be a promising structure to obtain enhanced performance for sub-20nm transistors and may be used for further scaling up the device.

We explore the effect of temperatures between 80 and 720 K on the energy and linewidth of zone-center transverse (TO) and longitudinal (LO) optical phonons in bulk gallium phosphide (GaP) using Fourier transform infrared ellipsometry from 0.03 to 0.60 eV. We extract the optical phonon parameters of GaP by fitting the ellipsometric angles with the Lowndes-Gervais model, which applies two different broadening parameters to the TO and LO phonons. In GaP, the two-phonon density of states is larger for the decay of TO phonons than for LO phonons. Therefore, we observed a larger TO phonon broadening (compared to the LO phonon) and an asymmetric reststrahlen line shape. This would lead to a negative imaginary part of the dielectric function just above the LO phonon energy, but the addition of two-phonon absorption avoids this. We find a temperature dependent redshift and broadening of TO and LO phonons with increasing temperature due to thermal expansion and anharmonic phonon-phonon scattering, involving three and four phonon decay processes. We also investigate the temperature-dependence of the high-frequency dielectric constant. Its variation is explained by thermal expansion and the temperature dependence of the Penn gap.

This article presents results of research work aimed at manufacturing photoconductive semiconductor switches (PCSSs) based on semi-insulating (SI) gallium phosphide (GaP) and gallium nitride (GaN). Currently, the work is in progress to determine the optimal values of PCSS parameters. In this article, the parameters of the selected semiconductor materials used for making PCSSs, the device operation principle, and possible areas of use are presented. The paper demonstrates the construction of test PCSSs based on SI GaP and SI GaN and results of blocking characteristics measurements without the illumination, as well as with illumination with a small photon flux. Further research directions are presented also.

Raman light scattering on phonons and polaritons is measured in a gallium phosphide sample. An unfocused beam of a 532-nm single-mode laser was used for excitation. A scattered radiation was collected using a mobile mirror of a small diameter, which allowed us to measure spectra of scattered light in a 0.6°–8° range of scattering angles with a total angular spread of 0.4°. For different crystallographic directions, intensities of polarized components of the Raman light scattering on longitudinal, transverse phonons and polaritons were measured in the region of a strong dispersion of the polaritonic branch for three fixed axial scattering angles. Components of scattering on longitudinal optical phonons and polaritons have a strong dependence on a crystallographic direction, as predicted by theory, and the component of scattering on transverse optical phonons did not depend on a crystallographic direction. It was found that the intensity of scattering on transverse optical phonons correlates with a width of a spectral line of scattering on polariton. A mechanism explaining this correlation is proposed.

Thin films of gallium-phosphorus-titanium (Ga-P-Ti) alloys were prepared on glass substrates at 573 K by an asymmetric bipolar pulsed direct current sputtering technique using an argon atmosphere and targets made from gallium phosphide (GaP) powder and metallic titanium (Ti), at the surface ratios of 8:1, 5:1, 2:1 and 1:1 GaP to Ti (GaP:Ti) on the sputtered area. Examination by X-ray diffraction, transmission electron microscopy, and field emission scanning electron microscope indicated that the as-deposited films from the sputtering targets having GaP:Ti ratios of 8:1, 5:1, and 2:1 were polycrystalline with the cubic zinc-blende crystal structure having GaP as the host material, i.e., Ti-doped GaP. Elemental compositions of the film obtained from the target at a GaP:Ti ratio of 5:1 closely resembled the theoretically predicted intermediate band compound Ga4P3Ti. It was projected that the Ga4P3Ti compound could be fabricated by co-sputtering of GaP and Ti from a single target having the surface area ratio GaP:Ti of 3.5:1. Optical transmission and reflection spectra, temperature dependence of electrical resistivity, and light response of the electrical resistivity showed semiconductor-like behavior for the films obtained from the targets with the GaP:Ti of 8:1 and 5:1, and were metal-like for those deposited from the other targets. Optical band gaps determined from the transmission spectrum of the semiconducting films by Tauc's expression for indirect transition were 1.2–1.5 eV. The results of the study could provide an alternative route for fabricating the intermediate band material based on the Ga-P-Ti system.

The spectral sensitization of single-crystal p-GaP by semiconducting single-walled carbon nanotubes (s-SWCNT) via hole injection into the p-GaP valence band is reported. The results are compared to SWNCT sensitized n-type single-crystal substrates: TiO2, SnO2, and n-GaP. It was found that the sensitized photocurrents from CoMoCAT and HiPco s-SWCNTs were from a hole injection mechanism on all substrates, even when electron injection into the conduction band should be energetically favored. The results suggest an intrinsic p-type character of the s-SWCNTs surface films investigated in this work.

Light-matter interactions with two-dimensional materials gained significant attention in recent years, leading to the reporting of weak and strong coupling regimes and effective nanolaser operation with various structures. Particularly, future applications involving monolayer materials in waveguide-coupled on-chip-integrated circuitry and valleytronic nanophotonics require controlling, directing, and optimizing photoluminescence. In this context, photoluminescence enhancement from monolayer transition-metal dichalcogenides on patterned semiconducting substrates becomes attractive. It is demonstrated in our work using focused-ion-beam-etched GaP and monolayer WS2 suspended on hexagonal boron nitride buffer sheets. We present an optical microcavity approach capable of efficient in-plane and out-of-plane confinement of light, which results in a WS2 photoluminescence enhancement by a factor of 10 compared to that of the unstructured substrate at room temperature. The key concept is the combination of interference effects in both the horizontal direction using a bull's-eye-shaped circular Bragg grating and in the vertical direction by means of a multiple-reflection model with optimized etch depth of circular air-GaP structures for maximum constructive interference effects of the applied pump and expected emission light.

In this work, the structural, electronic and optical properties of pure and aluminum (Al) doped gallium phosphide (GaP) in zinc-blende (ZB) phase are elaborated using full potential linearized augmented plane wave (FP-LAPW) method as implemented in Wien2K code. The calculated lattice parameters show decreasing behavior with increasing the concentration of Al contents. Band gaps of AlxGa1−xP are investigated by generalized gradient approximation (GGA) and found to be the increasing linear behavior by increasing the concentration of Al. Furthermore, the optical properties including dielectric constants, refractive index, reflection coefficient, absorption coefficient and extinction coefficient of AlxGa1−xP at different compositions are also calculated and discussed. In order to check the mechanical behavior under the influence of applied pressure the elastic coefficients of all these composition have been calculated and discussed. Calculated parameters i.e. lattice constants, band gaps, and optical variables are very close to the experimental values which suggested that the materials are good candidates for the opto-electronic devices. Further, the elastic constants for all compounds which describes the mechanical behavior are reported for the first time and there is no data available for comparison.

In this work, we study the structural phase transitions of gallium phosphide (GaP), witha combination of molecular dynamics simulations (MD) and ab initio calculations based on density functional theory (DFT) with vibrational corrections within the harmonic approximation, for pressures up to 50 GPa. We show that the transition sequence depends on temperature for both cases. For low temperatures, our MD simulations predict a transition sequence zinc blende → β -tin → Immm → NaCl, while DFT predicts the sequence zinc blende → Sc16 → β -tin → Immm. Our DFT calculations with vibrational corrections also indicate that, for high temperatures, the Sc16 phase gradually loses stability and other structures such as Cmcm, β -tin and NaCl become more stable. The kinetic effects are also studied by dynamically changing the pressure in MD simulations up to 200 GPa. We show that, as we increase the pressure, a transition to the β -tin structure should not occur at room temperature due a large energy barrier. For higher temperatures, we show that the first transition is zinc blende → NaCl. The differences in the observed transition sequence at low and high temperatures indicate that the vibrational corrections included in the DFT calculations are fundamental to the description of the stability of higher pressure structures, as also observed on other semiconductors. Moreover, the good agreement between DFT and MD shows the suitability of the classical effective many-body interaction potential, used to describe the different high-pressure phases of GaP.

A design approach for flat metasurface devices is proposed and applied to design the broadband reflectors in the visible regime. Firstly, the geometry parameters of metasurfaces which comprise a monolayer amorphous titanium dioxide nanorod array in the air are optimized to achieve a broadband perfect reflector whose bandwidth is about 90 nm. Further, for practical application, the geometry parameters of a metasurface which is composed with a monolayer gallium phosphide nanoparticle (rod or cuboid) array on a glass substrate are optimized to achieve excellent reflection performance. Such all-dielectric metasurface near perfect reflectors can be used to protect surfaces against high power irradiation and create low loss mirrors in laser cavities. The design approach presented in this work is based on utilizing genetic optimization algorithm in order to determine the scatterers dimensions and lattice period within a unit-cell of the metasurface. The approach exhibits great superiority on the design of perfect reflectors and can be extended to design more complex flat components such as metalenses, holograms and deflectors. This approach is expected to provide a guideline for designing multifunctional photonic metamaterial devices.

One-dimensional semiconductor nanowires often contain polytypic structures, owing to the co-existence of different crystal phases. Therefore, understanding the properties of polytypic structures is of paramount importance for many promising applications in high-performance nanodevices. Herein, we synthesized nanowires of typical III–V semiconductors, namely, gallium phosphide and gallium arsenide by using the chemical vapor transport method. The growth directions ([111] and [211]) could be switched by changing the experimental conditions, such as H2 gas flow; thus, various polytypic structures were produced simultaneously in a controlled manner. The nanobeam electron diffraction technique was employed to obtain strain mapping of the nanowires by visualizing the polytypic structures along the [111] direction. Micro-Raman spectra for individual nanowires were collected, confirming the presence of wurtzite phase in the polytypic nanowires. Further, we fabricated the photodetectors using the single nanowires, and the polytypic structures are shown to decrease the photosensitivity. Our systematic analysis provides important insight into the polytypic structures of nanowires.

The paper presents a study of tensoresistive characteristics of p-type GaP whiskers with [111] crystallographic orientation coinciding with the direction of the maximal piezoresistive effect for this material. The authors present a newly-developed technology of creating the ohmic contacts to GaP crystals that allows using these crystals at high temperatures (400—600°C). Tensoresistive characteristics of p-type GaP whiskers were studied in the strain range of ±1,2•10–3 rel. un. These studies show that the gauge factor for these crystals at 20°C is rather large. Thus, for p-type GaP crystals with a resistivity of 0.025—0.03 Ω•cm, the gage factor is in the range of 90—95. The study of tensoresistive properties shows that in the temperature range of 20—300°C for p-type GaP crystals with the resistivity of 0,01—0,03 Ω•cm, the gage factor decreases as the temperature rises, but in the temperature range of 300—550°C for this crystals, very slight temperature dependence of the gage factor was observed. In this temperature range, the temperature coefficient of gage factor is no more than –0,03%/°Ñ. In the temperature range of 300—500°C, the value of gage factor is high (40—50). It could be noticed that in the entire investigated temperature range, the strain sensors based on p-type GaP whiskers have the linear resistance vs. strain dependence in the strain range of ±5,0•10–4 rel. un. The developed strain sensors based on p-type GaP whiskers have high mechanical strength at the static and dynamic strain (more than 108 cycles), which makes them operable in dynamic mode.

A novel design of Hexa Sectored Photonic Crystal Fiber (HS-PCF) with high nonlinearity and high birefringence has been revealed in this paper where core is slotted and filled with Gallium Phosphide (GaP). Finite Element Method has been used for numerical investigation of the proposed PCF along with finer mesh. Different optical parameters like nonlinearity, effective area, power fraction, birefringence, confinement loss and Numerical Aperture (NA) have been explored by proper tuning of Geometrical variables. The investigation shows that, proposed PCF exhibits high nonlinearity of 9.47 × 104 W−1Km−1 at the operating wavelength of 1.4 µm along with high birefringence of 0.259, Numerical aperture of 0.8774 and very low confinement loss of 5.78 × 10−9 dB/m at the optical wavelength of 2.0 µm. Therefore, it is expected that this proposed PCF could be a strong candidate in biomedical imaging, super continuum generation and sensing applications considering polarized light. Keywords: Photonic crystal fiber, Birefringence, Low confinement loss, Nonlinearity, GaP strips, Slotted core

This contribution brings novel concept of Ag islands formation in 2D periodic arrangement with square symmetry on special 3D surfaces – gallium phosphide (GaP) nanocones, for surface-enhanced Raman spectroscopy application. 2D periodic structure in square symmetry with period of app. 470 nm is patterned in photoresist layer by interference lithography using double exposure of a two-beam interference optical field. Two different techniques for photoresist deposition on 3D surface are compared: spin-coating and photoresist deposition from water level. After Ag sputtering and lift-off, GaP nanocones are decorated with Ag islands in 2D periodical arrangement. Detectable enhancement in Raman signal for Rhodamine 6G adsorbed on prepared samples is demonstrated.

In order to overcome the limitations of silicon-based electronics, the integration of optically active III-V compounds is a promising approach. Nonetheless, their integration is far from trivial and control as well as understanding of corresponding growth kinetics, and in particular the occurrence and termination of antiphase defects, is of great relevance. In this work, we focus on the three-dimensional reconstruction of such boundaries in gallium phosphide from single scanning transmission electron microscopy images. In the high angle annular dark-field imaging mode, the appearance of these antiphase boundaries is strongly determined by the chemical composition of each atomic column and reflects the ratio of transmitted anti- to mainphase. Therefore it is possible to translate measured intensities to the depth location of these boundaries by utilizing simulation data. The necessary spatial resolution for these column-by-column mappings is achieved via electron optical aberration correction within the microscope. Hence, the complete 3D orientation of these defects can be measured at atomic resolution and correlated to growth parameters. Finally, we present a method to reconstruct large areas from well sampled images and retrieve information about complex embedded nanoscale structures at the atomic scale.